1. Field of the Invention
This invention relates to metal bonding using explosive energy. More specifically, the invention is an apparatus and method for wire splicing using an explosive joining process.
2. Description of the Related Art
Demand is increasing within the electrical industry for highly reliable metal joining of conductor wire providing physically and electrically integral bonds suitable for the geometries and working conditions encountered under wire joining. Interest also exists in remote metal joining of wire with metallurgically pure bonds for inaccessible operations such as assembly of structures in space. Prior art methods in cable manufacturing facilities include splicing conductor wires by a high-temperature joining process such as brazing. Annealing subsequently results and weakens the wires adjacent to the joints. Brazing also has the disadvantages of requiring skilled operators and prolonging installment time.
Explosive joining offers characteristics to satisfy both the demand in physically and electrically integral bonds and the interest in remote metal joining. This type of joining produces metallurgical bonds that do not deteriorate the wires in the area adjacent to the splice. Instead, the explosive joining process creates a high velocity, angular collision between the metal surfaces which causes formation of interatomic, electron-sharing linkups.
Previous methods of explosive joining for wire splicing, however, fail to disclose any method or apparatus that provides a reliably strong metallurgical bond for the connection of multi-strand wires with relatively easy assembly. For example, the prior art disclosed in U.S. Pat. No. 3,995,741 by Hofer anticipates the connection of multi-wire cables and braids but does not ensure a good metallurgical bond in each strand. Further, Hofer requires the gluing of a welded cartridge and the fitting of a sleeve over another sleeve during its time-delaying assembly. The prior art disclosed in U.S. Pat. No. 4,057,187 by Cranston et al, on the other hand, does not even disclose or suggest bonding of multi-strand wire for its device with a coaxial arrangement. Cranston also requires layering an explosive mixture upon a ferrule and then applying a protective coating over this explosive layer. Thus, Cranston also requiers a time-consuming assembly.
Previous methods of explosive joining are also limited because they require using relatively large amounts of explosive which present problems in safe handling and accurate operation. For example, Cranston recommends use of a primary explosive in a mixture necessitting experimentation to determine the amount and thickness of the explosive layer required to obtain a desirable metallurgical bond. Further, impacts, electrical shocks, heat, and fire could unintentionally ignite the primary explosive, thereby increasing the hazards of handling and operation. Large amounts of explosive may also result in damage to thin wires.